In addition, when the papilla is largely incised by the papillotome, the calculus is easily extracted. However, when a blood vessel near the papilla is cut, bleeding is caused. In general, incision up to an upper edge of a projection on an entrance side of the papilla is referred to as large incision, two thirds of the incision is referred to as medium incision, and one third of the incision is referred to as small incision. Since a possibility of existence of a blood vessel more increases as nearer to the upper edge of the projection, a possibility of bleeding is higher in the medium incision than in the small incision and is higher in the large incision than in the medium incision. In general, an opening of about 5 mm is formed by the medium incision. Since the opening has a stretching property to some extent, a calculus having a size up to about 10 mm can be discharged. Today, the medium incision is mainly performed from the viewpoint of a risk of bleeding. The calculus having a size up to about 10 mm is collected without destruction, however, a calculus having a size more than 10 mm is collected using a complicated procedure, as described above.
As a method having a small risk of bleeding, there is a method of expanding the papilla by a dilation balloon having a withstand pressure instead of the incision with the papillotome.